Implanted medical devices such as venous and arterial catheters, neurological prostheses, wound drains, urinary catheters, central venous catheters, peritoneal catheters, shunts, and other luminal indwelling devices, are useful for treating various medical conditions. However, a drawback of implanted medical devices is the risk of infection while the medical device is inserted in the body, and thereafter. Such risk exists even though the medical devices are sterilized and carefully packaged to guard against introduction of microbes or pathogens during implantation or insertion of the medical device. For example, there is a risk of serious nosocomial infections when using catheters for hemodialysis procedures. In fact, central venous catheters account for most nosocomial catheter-related bloodstream infections.
When catheters and other indwelling luminal devices are inserted into body cavities such as the urinary tract, venous or arterial vessels, bacteria or other microbes can be picked up from the skin and carried into the insertion site where bacterial or microbial colonization may ensue. Infections may derive from an interaction of the microbes and the catheter micro-surface. Once infected, the microorganisms adhere to the catheter micro-surface and rapidly become encased in a polysaccharide matrix or biofilm, which protects the microorganisms from a host's defenses.
In the case of urinary and venous catheters, there is a significant threat of microbial growth along the exterior surface or outer wall of the catheter and, especially for catheters used long-term, there is a significant threat of microbial growth along the interior surface or inner wall. This can lead to chronic urinary tract infections (CUTI), or septicemia in the case of venous and arterial catheters, thrombolytic emboli, stenosis, and thrombosis resulting from infections, and other life threatening complications, especially among the elderly and immuno-compromised patients. Thus, there is a need for the development of better methods of preventing and treating infections caused by the insertion of catheters into a patient's body.
In addition to antimicrobials, other therapeutic agents may help reduce complications associated with chronically implanted indwelling medical devices in the body of a patient. Such medications include anti-inflammatories, anti-proliferatives and anti-coagulating agents or a combination thereof. However, to be effective the therapeutic agent should be delivered to a substantial portion of the surface of the indwelling medical device. Without such therapeutic agents, there is a risk that portions of the medical device will become compromised and cause an inflammatory response and/or allow tissue in-growth over surfaces of the indwelling portion of the medical device.
Other drawbacks of conventional indwelling catheters include a significant crossing profile, lack of convenience, and tissue damage to the areas to which the catheters are deployed. For example, indwelling catheters are typically used only periodically. As a result, inconvenient characteristics of catheters, such as being difficult to thread or insert catheter bodies, add to the treatment time and potential discomfort of therapy provided by the catheter. Also, as discussed above, indwelling catheters, such as central venous catheters, may cause damage to a patient's vasculature.
Accordingly, there is a need for a medical device that can effectively deliver a therapeutic agent to a substantial portion of its surface, e.g. a substantial length of the outer surface of an indwelling catheter. In addition, improved devices are needed which feature a lower profile, more convenient method of use, and reduce tissue damage caused to a patient's anatomy.